I would like to see Virtualmin be able to easily maintain each "service" on separate machines while keeping the control panel itself centralized.
Server #1 - Virtualmin
Server #2 - HTTP/HTTPS/FTP
Server #3 - SMTP
Server #4 and Server #5 - DNS
Server #6 - IMAP/POP
The idea behind this type of deployment, would be to make the "Virtualmin" server do the management, and the other servers to run individual services, along with a simple "agent" which allows the "Virtualmin" server to control it remotely. (probably via SSH or an HTTP-API)
The overall goal is to allow for seamless and easy cluster management in a way that allows the "Virtualmin" server to distribute various tasks to different physical systems and/or VPS systems.
Ultimately, one would be able to deploy a "single" server setup where all "services" run from the same box (like the current VIrtualmin) or divide the tasks amongst any number of boxes accordingly, while keeping one central management point.
While I hate to refer to this; SWSoft is known for designing products this way (both their own and acquired products accordingly) The most notable product while being design for "Windows" is HELM.
If you were to adopt this type of system design, you could easily adjust your licensing which could generate more income for you guys.
I do not believe this idea conflicts with Cloudmin, but feel free to correct me if I'm wrong. In fact, I believe it would actually compliment Cloudmin, where Cloudmin could be used to manage the creation of cluster nodes to be used in the manner noted above.
Anyways, that's my two cents! (as usual)